Evaluation and Improvement of Geopositioning Accuracy of IKONOS Stereo Imagery

IKONOS imagery has been used in many commercial, government, and research applications ranging from environment monitoring, to coastal change detection, and to national security. The high costs of IKONOS high end products (Pro and Precision products) make it extremely attractive to find practical methods that use lower-cost IKONOS Geo products to produce highly accurate mapping products. This paper presents four different models defined in both object space and image space to refine the rational function derived ground coordinates. The models are the translation, scale and translation, affine, and second-order polynomial models. Different configurations of ground control points (GCPs) are carefully examined to evaluate the impact on accuracy improvement. The models are tested based on two IKONOS stereo pairs acquired in the Lake Erie coastal area. It is demonstrated that if an appropriate model and GCPs are used, ground point errors can be reduced from $5–6\text{to}1.5\mathrm{m}$ in horizontal and from $7\text{to}2\mathrm{m}$ in vertical directions.